src/org/ibex/core/Scheduler.java

   1 // Copyright 2000-2005 the Contributors, as shown in the revision logs.
   2 // Licensed under the GNU General Public License version 2 ("the License").
   3 // You may not use this file except in compliance with the License.
   4
   5 package org.ibex.core;
   6
   7 import java.io.IOException;
   8
   9 import org.ibex.js.*;
  10 import org.ibex.util.*;
  11 import org.ibex.graphics.*;
  12 import org.ibex.plat.*;
  13
  14 /** Implements cooperative multitasking */
  15 public class Scheduler {
  16
  17     // Public API Exposed to org.ibex /////////////////////////////////////////////////
  18
  19     private static Scheduler singleton;
  20     public static void add(Callable t) { Log.debug(Scheduler.class, "scheduling " + t); Scheduler.runnable.append(t); }
  21     public static void init() { if (singleton == null) (singleton = Platform.getScheduler()).run(); }
  22
  23     private static Callable current = null;
  24
  25     private static volatile boolean rendering = false;
  26     private static volatile boolean again = false;
  27
  28     /** synchronizd so that we can safely call it from an event-delivery thread, in-context */
  29     public static void renderAll() {
  30         if (rendering) { again = true; return; }
  31         synchronized(Scheduler.class) {
  32             try {
  33                 rendering = true;
  34                 do {
  35                     // FEATURE: this could be cleaner
  36                     again = false;
  37                     for(int i=0; i<Surface.allSurfaces.size(); i++) {
  38                         Surface s = ((Surface)Surface.allSurfaces.elementAt(i));
  39                         do { s.render(); } while(s.abort);
  40                     }
  41                 } while(again);
  42             } finally {
  43                 rendering = false;
  44             }
  45         }
  46     }
  47
  48
  49
  50     // API which must be supported by subclasses /////////////////////////////////////
  51
  52     /**
  53      *  SCHEDULER INVARIANT: all scheduler implementations MUST invoke
  54      *  Surface.renderAll() after performing a Callable if no tasks remain
  55      *  in the queue.  A scheduler may choose to invoke
  56      *  Surface.renderAll() more often than that if it so chooses.
  57      */
  58     public void run() { defaultRun(); }
  59     public Scheduler() { }
  60
  61
  62     // Default Implementation //////////////////////////////////////////////////////
  63
  64     protected static Queue runnable = new Queue(50);
  65     public void defaultRun() {
  66         while(true) {
  67             current = (Callable)runnable.remove(true);
  68             try {
  69                 // FIXME hideous
  70                 synchronized(this) {
  71                     for(int i=0; i<Surface.allSurfaces.size(); i++) {
  72                         Surface s = (Surface)Surface.allSurfaces.elementAt(i);
  73                         if (current instanceof JS) {
  74                             s._mousex = Integer.MAX_VALUE;
  75                             s._mousey = Integer.MAX_VALUE;
  76                         } else {
  77                             s._mousex = s.mousex;
  78                             s._mousey = s.mousey;
  79                         }
  80                     }
  81                     Log.debug(Scheduler.class, "performing " + current);
  82                     current.run(null);
  83                 }
  84                 renderAll();
  85             } catch (JSExn e) {
  86                 Log.info(Scheduler.class, "a JavaScript thread spawned with ibex.thread() threw an exception:");
  87                 Log.info(Scheduler.class,e);
  88             } catch (Exception e) {
  89                 Log.info(Scheduler.class, "a Callable threw an exception which was caught by the scheduler:");
  90                 Log.info(Scheduler.class, e);
  91             } catch (Throwable t) {
  92                 t.printStackTrace();
  93             }
  94             // if an Error is thrown it will cause the engine to quit
  95         }
  96     }
  97 }